Table 1 Characteristics of the included studies

[15]

GCS score ≤13, persistent severe respiratory distress, Po₂ <60 mmHg despite oxygen supplementation, an increase in PaCO₂ >5 mmHg

56 patients (recruited between January 1999 and August 2000), mean APACHE II score 19.5, mean age 64 years, mean PaCO₂ at presentation 40 mmHg

Variable CPAP (10–16 cmH₂O), variable BiPAP (starting from 15 and 10 cmH₂O; maximum not described)

Proportion of patients with hospital mortality and requiring intubation, the duration of noninvasive ventilation needed and hospital length of stay

Allocation concealment adequate; study not blinded; 3.6% of patients did not have pulmonary oedema were excluded from analysis; analysis was by intention to treat; Jadad scale score 3

[9]

Severe respiratory distress, inability to tolerate or synchronize with the mask, further deterioration in vital signs or significant haemodynamic compromise, Po₂ <60 mmHg despite oxygen supplementation, an increase in PaCO₂ >5 mmHg

36 patients, mean APACHE II score 18, mean age 77 years, mean PaCO₂ at presentation 50 mmHg

Fixed CPAP (10 cmH₂O), fixed BiPAP (15 and 5 cmH₂O)

Proportion of patients with hospital mortality and requiring intubation, new onset acute myocardial infarction, duration of noninvasive ventilation needed and hospital length of stay

Allocation concealment not clear; double blinding; 22% of enrolled patients did not have pulmonary oedema and were excluded from analysis, and 2.8% were excluded because of delay in starting CPAP; analysis was not by intention to treat; Jadad scale score 5

[14]

Intubation determined by the attending physician but criteria were not described

16 patients (recruited between May and October 1997), mean APACHE II score not available, mean age 69 years, mean PaCO₂ at presentation 40 mmHg

Variable CPAP (5–12.5 cmH₂O), variable BiPAP (starting from 8 and 3 cmH₂O; maximum not described)

Proportion of patients with hospital mortality and requiring intubation, duration of noninvasive ventilation needed

Allocation concealment not clear; not blinded; no loss to follow up; analysis by intention to treat; Jadad scale score 2

[16]

Respiratory arrest, respiratory pauses with loss of consciousness, agitation making nursing care impossible and requiring sedation, haemodynamic instability with systolic blood pressure <70 mmHg, and the clinician could elect to intubate if they felt that the patient's condition was not improving satisfactorily

71 patients, mean APACHE II score not available, mean age 74 years, mean PaCO₂ at presentation not available

Variable CPAP (5–20 cmH₂O), variable BiPAP (starting from 10 and 5 cmH₂O; maximum 20 and 5)

Proportion of patients with hospital mortality and requiring intubation, the duration of noninvasive ventilation needed and hospital length of stay

Allocation concealment not clear; not blinded; no loss to follow up; analysis by intention to treat; Jadad scale score 2

[18]

Respiratory arrest, respiratory pauses with loss of consciousness, agitation making nursing care impossible and requiring sedation, haemodynamic instability with systolic blood pressure <70 mmHg

46 patients (recruited between March 2002 and March 2003), mean APACHE II score 18, mean age 77 years, mean PaCO₂ at presentation 54 mmHg

Fixed CPAP (10 cmH₂O), variable BiPAP (starting with 15 and 5 cmH₂O; titration of inspiratory pressure to achieve tidal volume >400 ml)

Proportion of patients with hospital mortality and requiring intubation, new onset acute myocardial infarction, duration of noninvasive ventilation needed

Allocation concealment adequate; not blinded; no loss to follow up; analysis by intention to treat; Jadad scale score 3

[17]

Respiratory arrest, respiratory pauses with loss of consciousness, agitation making nursing care impossible and requiring sedation, haemodynamic instability with systolic blood pressure <70 mmHg

36 patients (recruited between January 2001 and January 2002), mean APACHE II score 18, mean age 77 years, mean PaCO₂ at presentation 63 mmHg

Fixed CPAP (10 cmH₂O), variable BiPAP (starting with 15 and 5 cmH₂O; titration of inspiratory pressure to achieve tidal volume >400 ml)

Proportion of patients with hospital mortality and requiring intubation, duration of noninvasive ventilation needed

Allocation concealment adequate; not blinded; no loss to follow up; analysis by intention to treat; Jadad scale score 3

[19]

Worsening clinical signs (respiratory rate >40 or <10 breaths/minute, reduced conscious level) associated with a falling arterial pH (less than at arrival and <7.2)

40 patients, mean APACHE II score not available, mean age 75 years, mean PaCO₂ at presentation 62 mmHg

Fixed CPAP (10 cmH₂O), fixed BiPAP (15 and 5 cmH₂O)

Proportion of patients with hospital mortality and requiring intubation, new onset myocardial infarction

Allocation concealment adequate; not blinded; no loss to follow up; analysis by intention to treat; Jadad scale score 3